Micro-motion devices may share a common architecture such that they have a main body of compliant material and some direct actuation elements (e.g., piezoelectric element). The shape of such a compliant material is designed with notches and holes on it, and in this way one portion of the material deforms significantly with respect to other portions of the material a motion in the conventional sense of the rigid body mechanism. The devices of this kind are called compliant mechanisms. Computer tools for the kinematical and dynamic motion analysis of the compliant mechanism are not well-developed. In this thesis a study is presented towards a finite element approach to the motion analysis of compliant mechanisms. This approach makes it possible to compute the kinematical motion of the compliant mechanism within which the piezoelectric actuation element is embedded, as opposed to those existing approaches where the piezoelectric actuation element is either ignored or overly simplified. Further, the developed approach allows computing the global stiffness and the natural frequency of the compliant mechanism. This thesis also presents a prototype compliant mechanism and a test bed for measuring various behaviors of the prototype mechanism. It is shown that the developed approach can improve the prediction of motions of the compliant mechanism with respect to the existing approaches based on a comparison of the measured result (on the prototype) and the simulated result. The approach to computation of the global stiffness and the natural frequency of the compliant mechanism is validated by comparing it with other known approaches for some simple mechanisms.

Micro-motion devices may share a common architecture such that they have a main body of compliant material and some direct actuation elements (e.g., piezoelectric element). The shape of such a compliant material is designed with notches and holes on it, and in this way one portion of the material deforms significantly with respect to other portions of the material a motion in the conventional sense of the rigid body mechanism. The devices of this kind are called compliant mechanisms. Computer tools for the kinematical and dynamic motion analysis of the compliant mechanism are not well-developed. In this thesis a study is presented towards a finite element approach to the motion analysis of compliant mechanisms. This approach makes it possible to compute the kinematical motion of the compliant mechanism within which the piezoelectric actuation element is embedded, as opposed to those existing approaches where the piezoelectric actuation element is either ignored or overly simplified. Further, the developed approach allows computing the global stiffness and the natural frequency of the compliant mechanism. This thesis also presents a prototype compliant mechanism and a test bed for measuring various behaviors of the prototype mechanism. It is shown that the developed approach can improve the prediction of motions of the compliant mechanism with respect to the existing approaches based on a comparison of the measured result (on the prototype) and the simulated result. The approach to computation of the global stiffness and the natural frequency of the compliant mechanism is validated by comparing it with other known approaches for some simple mechanisms.

This study has been carried out to develop and manufacture piezoelectric ceramic materials which are utilized for ultrasonic motor (USM) applications. For this purpose, the effect of compositional modifications on the dielectric and piezoelectric properties of lead zirconate titanate (PZT) based ceramics was investigated. PZT based powders were produced using the mixed oxide method. The base composition was selected as Pb(Zr0.54Ti0.46)O3. The samples in the proximity of morphotrophic phase boundary were doped with strontium, lanthanum, lead manganese niobate (PMnN) and lead manganese antimonate (PMS) in order to improve the structural characteristics and electromechanical properties which are very important for USM applications. The dielectric constant, planar coupling coefficient, mechanical quality factor, piezoelectric strain constant and tangent loss values were evaluated in accordance with standard IRE (Institute of Radio Engineers) test procedures. The results on dielectric and piezoelectric properties showed that piezoelectric ceramics with high mechanical quality factor, high piezoelectric strain constant and low tangent loss could be produced by using the aforementioned dopants. As a result, a new piezoelectric ceramic named as 0.97[PSLZT]-0.024[PMnN]-0.006[PMS] was produced with KT= 1913, Qm= 1240, d33= 540 pC/N, tan delta= 0.89%, kp= 0.57 and Tc= 235 &deg / C. This composition is a good candidate for high power applications. The ceramic samples with the developed compositions were used to produce an ultrasonic-wave type motor and the performance of the USM was evaluated in terms of speed, torque and efficiency.

The pipeline is playing an important role in industry nowadays. However, the inner wall of pipeline may suffer corrosion after a long service time. When excessive corrosion occurred, not only the transported material inside the pipe will let out but also serious accident may be induced. So, it¡¦s necessary to monitor pipeline thickness regularly. Conventionally, since most piping systems were subjected to high-temperature working environments, hence if an operator intend to examine the thickness of a pipeline, the whole piping system need to be shutdown and resulted in financial losses. Therefore, to develop on-line thickness measurement technique for pipelines subjected to high-temperature working environment is indispensable. ¡@¡@In this study, low-cost PZT sensors (Pb(ZrxTi1-x)O3), which can sustain high-temperature working environment, were used to execute the thickness measurements. A single PZT, which was bonded on the surface of a pipe as an actuator and a receiver simultaneously. Then, by utilizing the GUI(Graphic User Interface) system, which was designed in this study, the echo signal can be analyzed and the thickness of the pipe can be determined on-line and automatically. It is noted that the wave speed changed as environmental temperature increased. So, in this study, by using A36 steel plates and steel tubes as a specimens, a modified temperature versus wave velocity curve was proposed.. The experimental results showed that non-conservative thickness measurements will be obtained if modified wave speed was not adopted when working temperature increased. keywords¡GThickness measurement, PZT sensor, GUI system, Modified wave velocity curve.

Auch im Zeitalter globaler Verfügbarkeit von Informationen in digitaler Form wird weiterhin gedruckt, denn zahlreiche Druckprodukte sind im Alltag bewährt und nur schwer zu ersetzen. Doch die Anforderungen an die Druckindustrie haben sich in den letzten Jahren deutlich gewandelt: Der Trend geht zu kleineren, differenzierten Auflagen bis hin zum personalisierten Drucken. Daraus erwächst die Forderung nach Technologien, die einen schnellen Wechsel zwischen den einzelnen Aufträgen ermöglichen. In dieser Arbeit wird ein Druckverfahren beschrieben, in dem als Bildträger ferroelektrische Keramikschichten eingesetzt werden. Diese Schichten lassen sich lokal umpolarisieren und ermöglichen so die Realisierung einer informationsgesteuerten Modifikation des elektrischen Oberflächenpotenzials. Die einzelnen Prozessschritte des Verfahrens werden kurz diskutiert und insbesondere die Teilprozesse der Entwicklung und des Transfers näher untersucht. Zur Beschreibung von elektrisch determinierten Transportvorgängen in elektrostatischen Druckverfahren wird ein einfaches Potenzialstufenmodell vorgeschlagen, das die gezielte Auslegung und Optimierung von einzelnen Systemkomponenten ermöglicht. Der Entwicklungsvorgang an ferroelektrischen Keramikschichten unterliegt dabei grundsätzlich den gleichen physikalischen Zusammenhängen wie die Entwicklung in anderen elektrografischen und elektrofotografischen Verfahren. Als Druckstoff wurden Flüssigtoner eingesetzt, die wegen ihrer kleinen Partikelgröße eine sehr gute Bildqualität erwarten lassen. Es werden grundsätzliche Modelle zur Ladungsentstehung an Tonerteilchen in nichtwässrigen Dispersionen zusammenfassend vorgestellt und eigene Untersuchungen zur Charakterisierung der elektrophoretischen Beweglichkeit und der Ladung pro Masse diskutiert. Für die Beschreibung der Transferprozesse zur Übertragung des Tonerbildes auf den Bedruckstoff werden Darstellungen aus der konventionellen Drucktechnik mit den für Trockentoner entwickelten Vorstellungen bezüglich der elektrostatischen Verhältnisse verknüpft. Der Einfluss der elektrischen Papiereigenschaften auf die erreichbare optische Dichte wird in eigenen Untersuchungen exemplarisch gezeigt. Unter Berücksichtigung der Forderung nach konstanten Bedingungen für die Entwicklung des Tonerbildes werden Optimierungskriterien für die Auslegung des Transferzylinders abgeleitet, und ein verbesserter Transferzylinder konnte erfolgreich getestet werden.

Lead zirconate titantate (PZT) is an electroceramic material with many important technological applications in sensing and computer memory. Some of these applications require the PZT based devices to operate in radiation fields where they will be exposed to a high flux of energetic, heavy and light, charged and uncharged particles. The risk to any device exposed to ionizing radiation is the accumulation of displacement and ionization damage. Significant damage accumulation over time can lead to property drifts and, in some cases, failure of the device to perform properly. The goal of the undertaking recounted in this dissertation was to study changes in the ferroelectric properties of PZT exposed to the neutron field of a research nuclear reactor and to help develop an understanding for the type of radiation induced defects that play a dominant role in the degradation process. Thin film PZT capacitors were prepared using a wet chemical technique. The capacitors were then irradiated in a 1 MW TRIGA research nuclear reactor at the University of Texas at Austin up to a maximum 1 MeV equivalent neutron flux of 5.2 x 10¹⁵ cm⁻². Following irradiation, electronic characterization of polarization-electric field hysteresis loops, first order reversal curves, and small-signal permittivity were performed to ascertain tendencies between irradiation dose and ferroelectric properties. The measurements indicate a drop in remanent polarization, a loss of domain wall mobility, shifts in local switching fields and the formation of dipolar defects. These effects are all attributed to the introduction of defects into the material through displacement damage cascades. Numerical models of the damage cascades were performed to determine the displacement concentration. Comparison of those values and the primary recoil spectrum with typical survival rates found in the literature suggest that both free point defects as well as defect clusters are produced in comparable if not larger concentrations. It is proposed that defect clusters play a more significant role in ferroelectric property change than previously believed. / text

Masters Research - Master of Philosophy (MPhil) / The growing need of creating a network of sensors in critical environment to monitor, sense and alert an operator about the environment gives rise to the research work carried out in the area of power supply to these sensors. Wireless sensors are usually designed to run on batteries. However, as the number of sensors increases and the devices decrease in size, there is clearly a need to explore alternatives to battery power for wireless sensors. Reliable, efficient and environmentally friendly energy harvesting methods could be adopted to design and build a new electronic device that could be used to replace or supplement batteries in wireless sensors. This thesis focuses on potential ambient sources of power that can be harvested to run low power wireless sensors in mining environments. It discusses several techniques for converting energy from such sources into useful electrical power. In particular, piezoelectric power conversion technique is described in detail. Drilling is a crucial component in both underground and surface mining. Water jet assisted drilling is an example of a new drilling technology employing wireless sensors. There are various forms of energy that could potentially be used to power wireless electronic sensors provided the waste energy can be tapped in an intrinsically safe way. In this particular project, the required power to run sensors could be generated by converting mechanical vibration produced from water jet assisted drilling into electrical energy with an intrinsically safe circuit. Various power scavenging methods were researched, but vibration-to-electricity conversion using piezo-ceramic material was selected as the most promising method for this project. Piezo-based energy conversion is not normally good for mining applications because of intrinsic safety issues. In the case of water jet assisted drilling, however, the environment is much more suitable for piezo-electric conversion. A detailed computer model for this type of power conversion has been developed. The mechanical model of the vibration spectrum is based on test data from the Contents 2 CRC-Mining group. A power conversion circuit has been built, detailed circuit simulations studied and the experimental results are demonstrated. An example vibration scenario consisting of (20x10^-6)rms strain is considered. Based on this, and a detailed model of a 70mmx25mm PZT piezoelectric patch with 0:2mm thickness, our computer simulation studies and experiments demonstrate the ability to harvest up to 210mW of power.

Aachen, Techn. Hochsch., Diss., 2007.

Zugl.: Aachen, Techn. Hochsch., Diss., 2007.

Würzburg, Universiẗat, Diss., 2008.